The present invention relates to the transmission of data, and more particularly to the transmission of data unobtrusively embedded in a video signal representing a television program in order to transmit additional information to a receiver of the television program, or to identify the originator of the television program.
A television program is generally broadcast live, or recorded for subsequent broadcasting or distribution to affiliates, licensees or the public on media such as video cassettes. These programs are usually copyrighted or otherwise proprietary to the originator. Unauthorized sale or broadcasting of these programs is difficult to prevent. It is frequently impractical to determine the source of the program that may have been used without permission. Additionally it may be desirable to transmit additional information along with the television program for use by affiliates and licensees.
In either event it would be beneficial to be able to include additional data in the video signal of the television program without interfering with the displayed picture as seen by a viewer. Methods to add information to a video signal without interfering with the viewable picture have concentrated on lines in the vertical interval. However, only a small number of lines are available for this purpose. Also these lines are removed by many pieces of video equipment and replaced with newly generated waveforms containing only synchronizing information. If the purpose of the information is to identify the source of the program, the lines containing additional information could intentionally be replaced so that the source could not be determined.
What is desired is an unobtrusive means for embedding data within the active video portion of a video signal.